The ability to efficiently introduce functional, exogenous macromolecules into living cells is severely restricted by the plasma membrane. The development of vectors to overcome this barrier, such as disabled virus, cationic lipids, and direct injection, currently offer the potential for advances in therapeutic intervention and basic genetic research. We propose to develop a novel, flexible, generic, and highly efficient protein and nucleic acid delivery system based upon VP22, a structural protein of the herpes simplex virus 1. VP22 exhibits a unique form of intracellular transfer, whereby it is capable of efficiently exiting the mammalian cell in which it is synthesized, diffusing locally, entering a neighboring cell, and translocating to the recipient cell nucleus. Significantly, fusion proteins between VP22 and a second polypeptide chain retain functional characteristics of both proteins. We propose to develop a specifically modified version of VP22 that will be capable of delivering functional nucleic acid or protein to the nucleus of cells. Our modified VP22 protein will be prepared and incubated in vitro with tagged protein or nucleic acid. Based upon the extremely high affinity between modified VP22 and the tag, modified VP22 will form a tightly bound complex with the tagged macromolecule. Presentation of this complex to naive cells will result in complex uptake and nuclear translocation through the action of VP22; the delivered DNA or protein will retain biological activity. In this Phase I study we will construct, express, and characterize the modified VP22 and demonstrate its ability to efficiently deliver functional DNA and protein into tissue culture cells. Subsequent Phase II research will enhance the system for increased flexibility and explore the use of modified VP22 for the delivery of protein and DNA into tissues of the intact mouse. PROPOSED COMMERCIAL APPLICATION This research is directed towards developing a generalized technology for easily and efficiently introducing functional protein and nucleic acid to the nucleus of living cells. Potential applications include delivery vector for therapeutic intervention, gene therapy, and basic research.